Technical description and composition of the BBK 55LEX-6027 TV, panel type and modules used. The composition of the modules.
BBK LED
Model: 55LEX-6027 / UTS2C
Chassis / Version: CV538H-A
Panel: LSC550FN22-W
LED driver (backlight): integrated into PSU
PWM LED driver: UCC25710
Power Supply (PSU): RS146S-4T03
PWM Power: PFC, PWM
MainBoard: CV538H-A
IC MainBoard: CPU: MSD6586PYE-8-SW, EMMC: KLM8G1GEME
Tuner: DVB-T2 & SAT
55LEX-6027 / UTS2C Specifications
BBK 55LEX-6027
General recommendations for TV LCD LED repair
Possible manifestations of defects
- TV BBK 55LEX-6027 does not turn on, does not respond to the remote control and control panel buttons, does not light or blink indicators.
Most often, with similar manifestations, the main power module RS146S-4T03 turns out to be faulty. In the absence of the necessary supply voltages in the secondary circuits of the converters, it is necessary to check the power switches and rectifier diodes for possible partial or complete breakdown.
In case of diode breakdowns in the secondary circuits, the converter can operate in an emergency mode of short circuit without output voltages, and with a short circuit in the power elements of the primary circuit, the mains fuse and / or the current sensor in the source of the key usually breaks off.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can disable it in key mode, or provoke an excess of the maximum current or voltage values. These can be circuits supplying a PWM controller, damper or frequency setting circuits, or OOS (negative feedback) elements in the stabilization circuit. PWM controllers (PWM) PFC, PWM, in the absence of external damage and short circuit between the terminals, are checked by replacing them with known good ones.
- There is no picture, but there is sound and all other TV functions are working. The image sometimes appears for a second immediately after switching on and disappears.
The backlight of the matrix (LED panel) is usually faulty in these cases. Usually the cause of the malfunction is in the breakage of the LEDs, or in the connectors of the LED strips, but sometimes the LED driver is also faulty.
When diagnosing, it must be borne in mind that it is impossible to check for an open in the circuit of the LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally a current source. Opening the panel, you can check each LED separately. Typically, Chinese multimeters will lightly light one 3-volt LED when the probes are connected to it in the forward direction. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of the LED health. In the event of a malfunction of the LED, its zener diode will either be cut off or pierced in the K / Z.
If the BBK 55LEX-6027 / UTS2C has no picture, but there is sound, often the LSC550FN22-W display backlight simply does not work. Moreover, in LED TVs, the LEDs inside the panel usually fail, less often the LED driver.
In such cases, you can see a barely noticeable image with a successful hit of external light on the screen.
Replacing the LEDs requires disassembling the LCD panel LSC550FN22-W - a process that requires experience and qualifications from the master. We do not recommend doing such work on your own to owners of TVs and craftsmen who do not have experience in repairing LCD panels
If there is no image, and the backlight is on, the screen becomes slightly lighter when turned on, and in an open TV, light is visible through the holes in the panel case.
In this case, the panel may also be faulty - damage to strips, loops, for example, as a result of moisture ingress after unsuccessful washing of the screen, the T-CON (Timing Controller) board may be faulty. But the main board MainBoard CV538H-A often turns out to be faulty, a software failure is also possible.
Then, first of all, you need to check the panel supply voltage, fuses on the T-CON board, as well as the supply and reference voltages of the column and line drivers - VGH, VGL, Vcom.
If these measurements are within normal limits, it is necessary to trace the passage of LVDS signals from the MainBoard CV538H-A with an oscilloscope, as well as synchronizing signals to the loops with drivers.
Flooded or unsuccessfully washed screens of LED TVs can be restored, in about half of the cases, usually if significant damage has not formed in the loops and panel strips.
READ HOW TO REPAIR THE TV LED BACKLIGHT --------------> HERE.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals the standby mode.
Repair or diagnostics of the CV538H-A motherboard should begin with checking the stabilizers and power converters required to power the microcircuits and matrix. If necessary, you should update or replace the software (software). When repairing an MB board, it is necessary to check its components CPU: MSD6586PYE-8-SW, EMMC: KLM8G1GEME. Defective elements must be replaced. If chips with BGA soldering technology are used, the problem in its implementation is detected by local heating of the chip.
If there is no reception of TV channels, but the TV is working properly from external devices, first of all, you need to check the supply voltage of the DVB-T2 & SAT tuner and update the software. I2C communication pulses must be monitored with an oscilloscope.
Users and owners of TVs should remember that attempts to self-repair the BBK 55LEX-6027 TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
Revision after repair of the backlight. RS146S-4T03. Information from the master.
Current sensor - four resistors 2.9 Ohm 2W and six planar 10 Ohm 0.5W.
Decrease the backlight current from 500 mA to 250 mA - removed two large 2.9 Ohm resistors and two planar 10 Ohm resistors from the back side of the RS146S-4T03 board in the current sensor.
Additional MainBoard Repair
The MainBoard CV538H-A is shown in the figure below:
CV538H-A
External view of the power supply
RS146S-4T03:
RS146S-4T03
Main features of the BBK 55LEX-6027 device:
Installed matrix (LED panel) LSC550FN22-W.
To power the backlight LEDs, a converter combined with a power supply is used, controlled by the UCC25710 PWM controller.
The formation of the necessary supply voltages for all nodes of the BBK 55LEX-6027 TV is carried out by the RS146S-4T03 power module, or its analogs using PFC, PWM microcircuits.
MainBoard - the main board (motherboard) is a CV538H-A module, using CPU chips: MSD6586PYE-8-SW, EMMC: KLM8G1GEME and others.
The DVB-T2 & SAT tuner provides reception of television programs and tuning to channels.
LED TV BBK 55LEX-6027 / UTS2C with LCD LSC550FN22-W, diagonal size 54.6 "(139 cm) 16: 9 format. The required screen brightness of 250 cd / m2 is provided by LED backlighting. The ratio of maximum to minimum brightness ( contrast) is 4500: 1. The display technology of the model is implemented with LED backlighting.
LSC550FN22-W sensor and MainBoard CV538H-A software realize high-quality UHD images at 3840x2160 pixels in 4K UHD, HDR standard. Image processing is implemented using modern High Dynamic Range (HDR) technology with an extended range of brightness gradations.
55LEX-6027 / UTS2C has built-in SMART software and pre-installed Android operating system. Internet connection can be made via Wi-Fi wireless connection. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), MKV, JPEG.
Speaker power 16 W (2x8 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV x2, audio x2, component, VGA, HDMI x3, USB x2, Ethernet (RJ-45), Wi-Fi 802.11n. A headphone output is provided. The digital tuner is capable of receiving television channels in the DVB-T, DVB-T2, DVB-C, DVB-S, DVB-S2 standards.
The power supply unit RS146S-4T03 is used.
Dimensions: with stand 1244x782x254 mm, without stand 1244x723x97 mm.
TV weight: with stand: 13.3 kg, without stand: 12.8 kg.
Attention! The LSC550FN22-W panel of the BBK 55LEX-6027 / UTS2C LED TV is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it flows down the glass onto the cables to make the TV unrepairable.